Assisted Migration: A Primer for Reforestation and Restoration Decision Makers

Presentations by lead professionals about assisted migration. The symposium was held in Portland, Oregon at the World Forestry Center on February 21, 2013 and sponsored by the USDA Forest Service Rocky Mountain Research Station, the University of Idaho and the Western Forestry and Conservation Association.

Charting Assisted Migration as a Climate Change Adaptation Strategy — Mary Williams, Michigan Technological University, Houghton, MIAssisted migration, defined as the movement of native plants to facilitate natural range expansion in direct management response to climate change, has gained attention as an adaptation strategy since 2007. Drawing from conventional reforestation practices and proposed adaptation strategies, we chart the implementation of assisted migration and provide re¬sources for researchers, landowners, and nurseries to facilitate collaboration and development of reforestation and restoration plans.

Knowledge of landscape variation in adaption and adaptive traits is important for guiding decisions of population movement for purposes of assist¬ed migration. Scientists study adaptation through gynecology studies which consider correlations between population variation in traits and the environments of source locations where they evolved, or through reciprocal transplant studies which compare responses of different populations from a range of source environments grown in the same or similar range of environments. Results from gynecology and reciprocal transplant studies of Douglas-fir are presented. Management options for responding to climate change are considered.

As background to addressing the questions of "When and where to em¬ploy assisted migration?" I briefly review the ways in which species have moved in response to historic climate change. I review lessons learned from natural climate responses for implications to concepts of native range, neo-native distributions, community resilience, novel climates and non-analog associations, "red queen" responses, the role of climatic refugia in maintenance of diversity, and pace of change following disturbance. With this background, I turn to issues regarding decision—making for assisted migration: when and where to employ it in the face of con¬temporary climate change. Effects to weight include invasiveness, genetic contamination, allelo-chemical and soil-nutrient alterations, penology, community interactions and species displacement, and influences on disturbance regimes. I review these considerations relative to the four fundamental options for climate adaptation planning: resistance, resilience, response, and realignment (restoration), and provide illustrative examples for each. In conclusion I comment on policy and regulatory opportunities and constraints relative to implementing assisted migration.

Seeing the evidence of climate change prompts many conservation and restoration professionals to ask: what can we do to help our natural systems adapt to these rapid catastrophic changes? One common answer is assisted migration of taxa unable to move or adapt rapidly enough. But, how do we identify which taxa? Or where to move them? To undertake a successful assisted migration program requires the synthesis of multiple lines of evidence that cut across disciplines. We will present the most common tools that are currently being employed to understand the potential impacts of climate change on select taxa of plants, and provide the back¬ground necessary to evaluate their effectiveness.

According to many, we are subject to two duties. First, it is morally wrong for human to cause a species to go extinct. Second, it is morally wrong to introduce a species into an area in which it is not native. Unfortunately, human-induced climate change will cause species to go extinct unless we relocate those species to areas outside their native range. Thus, we are either causing species to go extinct or creating exotic species both of which are morally wrong. In this talk, I consider ways of dealing with the environmental dilemma.

To avoid extinctions and other harms to ecological health from escalating climatic change, scientists, resource managers, and activists are considering and even engaging in "assisted migration" - the intentional movement of an organism to an area in which its species has never existed. In this talk, I explore the profound implications of climate change for American natural re¬source management through the lens of this controversial adaptation strategy. I detail arguments regarding the scientific viability and legality of assisted migration under the thicket of laws that govern natural resources in the United States. I explain why contemporary natural resource law’s fidelity to historic baselines, protecting preexisting biota, and shielding nature from human activity is increasingly untenable, particularly in light of climate change. Active, anticipatory strategies such as assisted migration may not only be permissible but even necessary to avert substantial irreversible harm to ecological systems. Scientists and resource managers should focus on developing scientific data to aid analyses of the risks and benefits of assisted migration in particular circumstances. To help develop such data while minimizing ecological harm, I propose provisionally limiting experimental translocations to situation where translocation is technically and economically feasible, and where the species is endangered, ecologically valuable, and compatible with the proposed site.

This presentation examines opportunities for creating new seed transfer systems and for implementing assisted migration, and discusses the design of seed transfer systems from the perspective of their structure, critical seed transfer distance calculation, and zone delineation methods, and ability to accommodate assisted migration. A hybrid fixed/focal point seed transfer system and methods to integrate assisted migration into existing fixed and focal point seed transfer systems will be proposed.

Assisted migration offers a means to maintain forest productivity and ecological function by expediting species movements. Identifying which seed sources to move to optimize goals will not be trivial task. With respect to reforestation, decisions regarding seed source have typically relied on natural seeding in, seed zone collections, or in special cases, information gleamed from common garden or provenance trials. Neither of the first two methods is guaranteed to produce a standing crop adapted to the future environment. Good provenance trials can significantly improve those chances, but offer a number of fiscal and logistical hurdles. Genomic studies, conducted at the landscape level, may potentially offer a suite of complementary, precision tools for guiding seed source selection assisted migration or other reforestation needs. This talk outlines the scientific basis of landscape genomics, reviews results of early studies in the field and discusses potential applications.